Air filter



y 1930- A. JQRDAHL 1,771,639

FILTER Original Filed March 10, 1923 v v A nv vavra 77 RNEY,

Patented July 29, 193.0

[UNITED STATES PATENT OFFICE annsns .ronnann, or-nnw Yonx, n. Y.,assmnoa 'ro mnarcan am rmrna ooi rrm, me, or noursvrnnn, KENTUCKY, a.conroaarron or nanawaaa AIR FILTER Original application illed mm; 10,1823, Serial No. 624,171. Divided and this application fled November 7,192a. Serial no. $11,730.

This invention relates to air filters, and has for its general objectand purpose to provide a novel and inexpensive filter structure for moreeffectively and efliciently removing 5 dust and other foreign matters orsolid impurities from air, gases and the like to be utilized either forpurposes of ventilation or in carrying out various industrial processesor operations.

To this end, the subject matter of the present application whichconstitutes a div1sion of my ending application Serial No. 624,171,filed arch 10, 1923, now Patent No. 1,743.675, issued Jan. 14,1930, inits essentials broadly contemplates the provision of means whereby theair or gas between its point ofingress to the filter and its egresstherefrom is subdivided into eddy currents progressively increasing innumber and velocity so that by the resultant inertia in the frequentchange in direction of such eddy currents, the solid particles offoreign matterare deposited and retained in the filter structure so thatthe air or gas will leave the filter in a highly urified condition.

It is another 0 ject of m invention to provide a filter for accomplising the above result, in which a mechanical filtering means is employed,so constructed and arranged as to obviate the serious clogging of thefilter by dust or dirt after a long continued period of operation. a r

In one practical embodiment of the invention, this novel filtering meanspreferably consists of a plurality of baflle elements which may be inthe simple and inexpensive form of corrugated expanded metal sheets soarranged relative to each other as to provide a plurality of series ofangular baffle vanes forming relatively large voids or pockets betweenthe metal sheets so that initially, the inflowing air or gas is brokenup into a number of separate streams or currents, which.

in their passage through the air pockets cause the larger and heavierparticles of foreign matter to be retained within said pockets and uponthe walls thereof. At the egress side of the filter, a single sheet ofthe expanded corrugated metal is arranged and between said sheet and theinnermost metal sheet a the o osite at of the filter, mineral wool ispositioned. This mineral wool 'throughoutyits area. Thus,the initialcompression of this mineral wool'when it. is placed within the filterwhich determines its resistance to the air or gas flow is also constantand invariable so that the volume of air or gas passing through thefilter in any predetermined interval'of time may be accuratelycalculated.

The mineral .wool subdivides the air streams into an infinitely greaternumber of small eddy currents. The velocityof flow of the 'air or. gasthrough this part of the filter is thereby greatly increased. It will beunderstood that such a mechanical filter is of the semi-dry t pe, or inother words, before use, all of the ltering material is thorou hl coatedwith a suitable viscous solution wiic acts by adhesion, to securely holdand retain the particles of dust or other solid matter imvpgnged againstsuch surfaces.

ith the above and other objects in view, the invention consists in theimproved filter and in the form, construction and relative arrangementof its several arts as will be hereinafter more fully described,illustrated in the accompanying drawings, and subsequently incorporatedin the subjoined claims.

In the drawings wherein I have shown one simple and practical embodimentof the invention, and in which similar reference characters designatecorresponding parts throughout the several views,-

Figure 1 is a fragmentary sectional view through an air or gas filterillustrating the essential characteristics'of the present improvements;

Fig. 2 is a fragmentary side elevation of one of the corrugated expandedmetal sheets constituting part of the filtering means, and

Fig. 3 is an edge view thereof.

Referring in detail to the drawing, it will first be seen from referenceto Fig. 1 that at the ingress side of the filter installation, I arrangeapluralityof deeply corrugated expanded metal sheets 5 in close abuttingcontact'with each other. Each of these metal sheets or filter elementsis expanded and formed to provide regularly spaced baflling vanes 6, thevanes in each series being equidistantly spaced apart and the adjacentseries of vanesbeing obliquely inclined in. relatively op ositedirections from the interveningpara el strips or sections 7 of the metalsheet which integrally-connect the vanes 6 with each other. Thisconstruction, results in the formation of relatively deep corrugationsbetween the ad'acent series of bafile vanes 6 at each side 0 the metalsheet.

The expanded corrugated metal sheets 5 at the ingress side of the filterare arranged with the sections 7 of said metal sheets in close abuttingcontact with each other, thereby providing a filter section of generalhoneycomb appearance having a series. or group of substantially rectanular voids or pockets. indicated at 8.boun edbythe inclined baflies 6 ofadjacent metal sheets.

At the egress side of the filter installation, there is arranged asingle expanded and corrugated metal sheet 9 preferably of the sameconstruction as the metal sheets 5.. Between this expanded sheet 9 andthe opposed metal tween said metal sheets and between the top,

. of this invention.

bottomand side walls of the air passage, or the cell casing within whichthe filtering material may be enclosed and confined.

Generally considered, the use of expanded metal sheets, and steel ormineral wool for air filtering purposes, is not new, but in so far as Iam aware, these filtering elements have never before been combined in afilter .installation in the manner herein disclosed and results and toaccomplish the purposes It is likewise common practice in the art, inthe semi-dry type of filter, to immerse this filtering material in amore or less viscous solution whereby the surfaces of, thematerialagainst which the air currents impinge will be completely coated orcovered by the solution and to which the particles of solid matter willadhere. It is however, a well known fact that when steel or mineral woolalone is used as a filtering medium enclosed within a cell between sidewalls of fine gauge metal screening or other air pervious material, owinto the weight of the-liquid coating on the fi rs of the material, itwill gradually settle leaving a space between the mass and the top wallof the filter cell or air passage. This results in a very appreciablevariation in density in the mass from its lower to its upper portion,and therefore, a corresponding variation or non-uniformity in theresistanceofi'ered by different areas or means course,

Re erring now to Fig. 1 of the drawing,

it will be noted that the fibrous mass of mineral wool 10 enters andcompletely fills the corrugations of the s aced metal shwts 5 and 9.Owing to the e th of these corrugations, numerous space oints-of su portare provided at each si e of the b0 y of mineral woolsuflicientlyadequate in the aggregate area of supporting contact betweensaid material and the expanded metal sheets to overcome all tendency ofthe mass to sag or settle b' the action of gravity between said metasheets. Thus, ,after the material 10 is initially compressed andrendered uniform in density when placed between the expanded metalsheets,such uniformity in density and resistance to air flow of the saidmaterial will be maintained throughout the life of the filter.

In operation, it will of course be understood that my new air filtering'means as above described may be utilized in a great variety of waysasmaybe necesitated by the exigencies encountered in difi'erentinstallations.For instance, my invention may be employedin the manner now commonlyadopted in this art by mounting and arranging the filtering elements ormaterials within a cell casinghaving 0 posite side walls of wirescreening, expan ed metal or other reticulated materials, and suchcells. sufiicient in number to entirely fill the air passage or conduitmay be removably mounted in a suitable supporting frame. Since this is acommon and well known practice in the art, illustration of such apractical installation, is not required for the purposes of the presentexplanation.

Regardless of the particular or specific manner of application of mypresent improvements, it will be apparent that upon the inflow of air orgas at the ingress side of the filter, it will first encounter theseries of expanded metal sheets 5. Upon striking against the first groupof bafiies 6, the air or gas is divided into a large number of separatestreams as it passes between the adjacent baflie vanes. -In similarmanner, these air streams impinge upon the succeeding series of bafilevanes 6 after passing through the intervening voids or pockets 8. Byreason of the oblique or angular relation of the bafiles with respect tothe general path of flow of the air, it is obvious that these airstreams must frequently change their direction or course as they passbetween the series ofbafile vanes and through the intervening voids orpockets 8. With each change in direction of the air streams, theparticles of solid foreign matter therein tend to pursue. a straightcourse and by inertia are deposited upon the the passage of unfilteredair viscous coated surfaces of the bafiles to which they willtenaciously adhere. Thus, the larger particles of dust or other foreignmaterials 1n the gas or air will be securely caught and held. By thesubdivision of the air into the separate streams or currents, there willof course, be an appreciable increase in velocity of the individual airstreams during their passage through the cellular section of the filterformed by the metal sheets 5.

After the air streams have passed through this first section of thefilter, they next encounter the fibrous mass of mineral wool 10. Theseveral air streams will here be broken up and subdivided into a greatnumber of e dy currents repeatedly changing their course or direction asthe impin e against the individual fibers of t e dense y packed mass 10.Of course, the voids between adjacent fibers in this mass are veryminute, and the velocity of the eddy currents in their pas sagetherethrough, is correspondingly greater than the velocity of the airstreams pass-' ing through the larger pockets or voids 8 formed by theexpanded metal sheets or elements 5. As above noted, the resistanceoffered to the passage of these eddy air currents throughout the mass ofthe material 10,

is uniform. In this filtering mass and upon the viscous coatedindividual fibers thereof, the finer or more minute particles of dustare caught and held so that when the air finally passes through theexpanded metal sheet 9 at the egress side of the-filter, it ispractically devoid of suspended forei n matters and is thoroughly cleanor puri ed. The importance of uniformity in its resistance to air flowin the mass of the material 10 will be appreciated when it is consideredthat in the carrying out of various chemical and industrial processesand operations, it is of first importance to accurately determine thevolume of filtered air supplied to the apparatus during a predeterminedincrement of time. Accordingly, it will be apparent that my presentimprovements result in the provision of a filtering apparatus'which willpossess great efiiciency and reliability when employed for suchpurposes.

From the foregoing description, the construction and advantages of myimproved air or gas filter as above described will be clearly and fullyunderstood. While my present disclosure, is exceedingly simple andinexpensive to manufacture and install, it likewise presents an entirelysatisfactory solution of a serious difiiculty heretofore existing inconnection with the industrial use of such air filters. As beforestated, the present improvements are not concerned with any particularmeans for the practical application of the novel structural features orprinciples of the invention to any specific installation, but isinclusive of all adaptations to which the air receiving pockets or voidsand o relatively low resistance to the 'assage of from said filtersection,

structural characteristics of the filter may be susceptible.

Accordingly, it is to be understood that in practice I reserve theprivilege of making all such legitimate changes in the mechanical formand details of the present disclosure as may be fairly considered aswithin the spirit an scope of the appended claims.

I claim: a

- 1. In an air and gas filter of the semi-dry t pe, a cellular sectionat the ingress sideof t e filter composed of rigid foraminous filtermembers cooperating to form a oupof ering a air, a foraminous memberlatera ly spaced and a contiguous filter section composed of a comressed fibrousv mass extending between the latter memberand saidcellular filter section, one of the filter members of the first namedfilter sec-,

tign having parts cooperating with said mass to sustain the same andmaintain a uniform density thereof, said compressed filter masspresenting a comparative y high resistance to the passa e of air. a l

2. In an air and gas filter of the semi-d type, a plurality of filteringsections inclu ing a ce lular'section composed of a plurality ofmetallic foraminous filter'members cosame and maintain the uniformdensity thereof, said compressed filter mass presenting a crmparative yhigh resistance to the passage 0 air.

' 3. In an air and gas filter, aoed ri 'd metal filtering membersarrangeifin para el vertical planes and each havin a succesison oflaterally convergent walls orming comparativel deep corrugations, andeach of said wal s consisting of uniformly s aced bafile vanes, and acompressed mass of fi rous metallic filtering material interposedbetween A said members and extending into the corrugations thereofwhereby said mass is sustained or supported between said conver entwalls and maintained at a predetermi uniform density presenting auniform resistance throughout said mass to the passage of airtheret-hrough.

4. In an air and gas filter of the semi-dry type, a filter structureembodying a plurality of metal sheets constructed and arranged toprovide a group of dust entrapping and retaining filter pockets ofsubstantially uniform area, a similar metal sheet spaced from said firstnamed metal sheets at one side thereof, and a viscous coated fibrousmaterial having foramlnous walls each arranged between the opposed saeed metal sheets and thereby connned un er ressure and sustainedagainst gravity settling to maintain said material at a constantpredetermineduniform density and resistance to the flow of the air orgas.

- 5. In an air and gas filter of the semi-dry ty a filter structureembodying spaced su antially rigid corrugated metal sheets provided withand laterally spaced evisconnected vertically resslbl horizontalportions, and a com cons coated material positioned metal sheets andhaving arts extending into the corrugations thereo and sustained by saidforaminous walls whereby the filtering mass is maintained in a formlycompressed condition to present an invariable and uniform resistanceto'the flow of the air or gas throughout the area of said mass. 7

6. In an air and gas filter of the semi-dry type, filtering meansofiering progressively increasing resistance to the gassa as betweentheingress an egress sides of the filter, said means embodying a cellularstructure at the i ress side 0 thefilter composed of a plurality ofrigid metal filtering members forming a group of air kets or voids andofiering comparatively ow resistance to the air flow, and a eonti ousfilter section of uniform porosity ofiermg an appreciably higherresistance to the passage of air or as.

In testimony that I claim the, foregoing as my invention, I have signedmy name hereto.

ANDERS JORDAHL.

tween said redetermined um ge of air or

